JP5110862B2 - Liquid crystal display device and control method thereof, computer program, and storage medium - Google Patents

Description

  The present invention relates to a liquid crystal display device, a control method thereof, a computer program, and a storage medium.

  In recent years, liquid crystal display devices have been used as TV receivers and PC display devices. Such a liquid crystal display device is widely used because it can be formed thin and saves space and power. However, such a liquid crystal display device has a problem that a response time until image data is actually displayed is long. Therefore, as a driving method of the liquid crystal display device for improving the response speed, a method is proposed in which image data to be displayed next is compared with previous image data and overdrive driving is performed according to the comparison result. (See Patent Document 1).

  Further, as shown in FIG. 13, when overdrive driving is performed only on one side (positive or negative) of AC driving, a DC component remains, and depending on the structure and configuration of the liquid crystal display device, reliability may be deteriorated. is there. For this reason, in a liquid crystal display device in which a pixel electrode and a counter electrode are arranged on the same substrate and a voltage is generated in parallel with the substrate, at least one of the pixel electrode and the counter electrode is generated by an ITO film, and reliability based on a DC component is obtained. A method for improving the deterioration of the property has also been proposed (see Patent Document 2).

In such a liquid crystal display device, by adopting a structure in which at least one of the pixel electrode and the counter electrode is formed of an ITO film, it is possible to improve the deterioration of reliability due to the remaining DC component due to overdrive driving. However, for this purpose, it is necessary to change the panel structure of the liquid crystal display device, and there is a problem that it cannot be applied universally to various liquid crystal display devices.
Japanese Patent Laid-Open No. 11-125050 JP 2001-34238 A

  As described above, conventionally, in the display device, the panel structure is not changed, the DC component unbalance due to the overdrive drive is eliminated, and the response speed and the reliability cannot be improved.

  Therefore, an object of the present invention is to eliminate the imbalance of DC components due to overdrive driving and improve the response speed and reliability in a display device without changing the panel structure.

The present invention for solving the above problems is a liquid crystal display device,
Liquid crystal display means driven by alternating voltage;
Conversion means for converting the input image data into N frame rates by dividing the input image data into N frames for each frame;
Correction means for correcting the drive voltage for driving the liquid crystal display means based on the difference between the image data temporally changing with respect to the image data converted by the conversion means,
Reversing means for reversing the polarity of the image data including the image data corrected by the correcting means so that the driving polarity of the image data before and after is different;
Drive means for driving the liquid crystal display means using the image data with the polarity reversed;
Control means for switching the order of reversing the polarity;
At least two or more input means for inputting the image data;
An input switching means for switching the two or more input means to input the image data from any one of them;
Receiving means for receiving a switching instruction for the input switching means;
Equipped with a,
When the switching instruction is received by the receiving means, the control means switches the order of inverting the polarity .

  According to the present invention, in the display device, the DC component unbalance due to overdrive driving can be eliminated and the response speed and reliability can be improved without changing the panel structure.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are not necessarily essential to the solution of the invention.

[First Embodiment]
FIG. 1 is a side view showing an example of a rear projection display device 200 according to an embodiment of the invention.

  In FIG. 1, the image projected from the projection display engine D <b> 1 is reflected by the reflection mirror 201 and projected from the back surface of the screen 6. A digitizer device 202 is attached to the front surface of the screen 6. When the position is designated with the digitizer pen 203 on the front surface of the screen 6 to which the digitizer device 202 is attached, the coordinates of the designated position can be input to the display device 200. As this digitizer device, various devices such as an optical device, a pressure-sensitive device, and an ultrasonic device can be used. The brightness adjustment switch 204 is a switch for adjusting the brightness of an image displayed on the screen 6.

  Next, the structure of the projection display engine D1 according to the embodiment of the invention will be described with reference to FIG.

  In FIG. 2, three liquid crystal panels 2R, 2G, and 2B corresponding to R, G, and B color displays are used as light modulation elements, and these three liquid crystal panels 2R, 2G, and 2B are located at positions facing the cross prism 7. Has been placed. In the present embodiment, TN liquid crystal panels that are driven using TFTs are used as the liquid crystal panels 2R, 2G, and 2B. Further, polarizing plates 8 are disposed on both sides of the liquid crystal panels 2R, 2G, and 2B, and a projection lens 9 and a screen (projected member) 6 are disposed on the light emission side of the cross prism 7.

  The parabolic reflector 10 is disposed so as to surround the lamp (light source) 1 so that the emitted light L1 from the lamp 1 is converted into a parallel light beam L2. The reflector 10 may be an elliptical type instead of a parabolic type and may be converted into a condensed light beam. As the lamp 1, a metal halide lamp, a xenon lamp, or the like can be used. Further, the fly-eye integrators 40 and 41 are arranged in a conjugate relationship with the liquid crystal panels 2R, 2G, and 2B on the optical path of the light emitted from the lamp 1, thereby improving the non-uniformity of the light source. ing. A relay lens 11 and a mirror 12 are sequentially arranged on the light exit side of the fly-eye integrators 40 and 41. Further, in the subsequent stage, two dichroic mirrors 13 and 14 are arranged, the light emitted from the lamp 1 is branched into three, relay lenses 15 and mirrors 16, 17, and 18 are arranged, and the respective liquid crystal panels 2R, 2G. , 2B. Reference numeral 19 denotes a field lens.

  Note that the liquid crystal panels 2R, 2G, and 2B described above are connected to a video signal input unit 3 as shown in FIG.

  Next, processing of electric signals in the projection display engine D1 according to this embodiment will be described. FIG. 3 is a block diagram showing an example of the configuration of the display engine of the display device 200 according to the embodiment of the invention.

  In the video signal processing unit 3, the switch 30 switches between a video signal input from the PC via the terminal 50 and an NTSC signal input from the terminal 51. The NTSC signal includes a video signal of a general television broadcast program. Also, a video signal obtained from a recording device (video deck, DVD recorder, HDD recorder) that records a video signal on a medium or a playback device (DVD player, LD player, etc.) that reproduces a video signal recorded on the medium included. The signal processing circuit 52 performs signal processing such as NTSC signal decoding, noise reduction processing, band limiting filtering, and signal level adjustment on the NTSC signal input from the terminal 51. The A / D converter 31 converts the input analog video signal into a digital signal.

  A DSP (Digital Signal Processor) unit 32 receives A / D converted digital image data, executes predetermined signal processing, and outputs the execution result to the frame rate conversion unit 101. The predetermined signal processing includes, for example, image processing such as contrast, brightness adjustment, color conversion, and resolution conversion. The frame rate conversion unit 101 converts the frame rate of the input image data. The memory 33 is a memory that holds current image data, image data to be displayed in the next frame, and the like.

  The timing generation circuit (TG) 34 outputs a timing signal that defines the operation timing to each unit. The memory 102 is a memory for storing previous image data in order to correct the response speed. The response speed correction unit 103 compares the image data output from the frame rate conversion unit 101 with the image data via the memory 102 and corrects the drive voltage to correct the response speed. The polarity inversion unit 106 inverts the polarity of the image signal based on the input image data.

  The polarity inversion control unit 131 instructs the polarity inversion unit 106 to change the polarity inversion order. The timing detection unit 132 detects timing for changing the order of polarity inversion. The D / A converter 35 converts the digital image data into an analog image signal and outputs it to the panel driver 36. A video signal and power are supplied to the RGB liquid crystal panels 2R, 2G, and 2B via the panel driver 36 by the analog image signal.

  Although only analog input signals are shown in FIG. 3, it is needless to say that it is effective to provide digital signal input terminals such as LVDS and TMDS, D4 terminals for digital TV, and the like.

  The ballast 57 is a lamp power source connected to the lamp 1. Reference numeral 58 denotes a power supply unit as power supply means for supplying power for operation of the display device 200, and reference numeral 60 denotes an AC inlet. The remote controller 61 is a remote controller that instructs various operations of the display device 200. The control panel 62 receives a signal from the remote controller 61.

  Reference numeral 204 denotes a brightness adjustment switch, and the brightness adjustment switch detection unit 109 detects the operation of the brightness adjustment switch 204. The digitizer detection unit 118 detects the coordinate position designated by the digitizer device 202. Reference numeral 107 denotes a USB interface (I / F). Furthermore, 63 indicates a CPU, 64 indicates a ROM, and 65 indicates a RAM. The CPU 63 is connected to the video signal input unit 3, the control panel 62, the ballast 57, the brightness adjustment switch detection unit 109, the digitizer detection unit 118, the USB I / F 107, and the like, and drives the liquid crystal panels 2R, 2G, 2B, the lamp 1, and the like. Control and enlarge / reduce or move the displayed image.

  In this embodiment, the brightness adjustment switch detection unit 109, the digitizer detection unit 118, the USB I / F 107, and the like have been described as being connected to the CPU 63. However, the brightness adjustment switch detection unit 109, the digitizer detection unit 118, and the USB I / F 107 may be built in the CPU or executed by a program. Good.

  Next, the configuration of a PC (personal computer) 300 connected to the display device 200 will be described. The PC 300 includes a CPU 301, an HD (hard disk) 302, a RAM 303, a ROM 304, a video memory 305, a graphic controller 306, a mouse I / F 307, a USB I / F 308, and the like. Furthermore, a video output terminal 309, a USB input terminal 310, and a mouse input terminal 311 are provided. The mouse 312 functions as a pointing device and is connected to the mouse input terminal 311.

  Next, the operation of the display device 200 according to the present embodiment will be described in detail with reference to FIGS. 3 and 4 to 8.

  First, in the display device 200, either the video signal input from the PC input terminal 50 or the video signal input from the NTSC input terminal 51 is selected by the switch 30. The selected video signal is converted from an analog signal to a digital signal by the A / D converter 31. Next, the DSP unit 32 performs image processing such as contrast, brightness adjustment, and color conversion on the digital image data. The image data output from the DSP unit 32 is further converted into a desired resolution and frame rate by the frame rate conversion unit 101.

  In the frame rate conversion unit 101, one frame is divided into N by image division. N is an arbitrary integer equal to or greater than 2, and the frame rate is N times according to the number of divisions. In this embodiment, as an example of N division, a case where N = 2, that is, a case where a video input signal having a vertical frequency of 60 Hz is converted into a frame rate having a double vertical frequency of 120 Hz will be described. At that time, the input image data of at least one screen is stored in the memory 33, and is converted into a divided image signal having a frame rate different from that of the input image signal by changing a reading speed of the image data from the memory 33. Is possible.

  4 to 8 show signals for driving specific pixels of the liquid crystal panel in each signal processing unit in the display device according to the present embodiment.

  First, FIG. 4 is a diagram illustrating a signal for driving a specific pixel of the liquid crystal panel input to the frame rate conversion unit 101. In FIG. 4, it corresponds to video input signals for 5 frames of 60 Hz. Among these, in the frames (1) and (2), a black signal is applied (voltage V0), and the halftone image data 1 (voltage V1) is changed in the frame (3). Further, in frame (4), the halftone image data 2 changes to brighter halftone image data 1 (voltage V2).

  Next, FIG. 5 is a diagram illustrating image data output from the frame rate conversion unit 101. In FIG. 5, each frame shown in FIG. 4 is represented as frame (1) in frames (1) and (1) ′, frame (2) in frames (2) and (2) ′ (hereinafter the same). It is shown divided into two frames.

  In the present embodiment, the frame rate conversion unit 101 converts the frame rate of the image from 60 Hz to 120 Hz. The frame rate conversion unit 101 converts the frame rate to double by continuously reading out the image data stored in the memory 33 twice. Next, in order to improve the response speed of the display device 200, the response speed correction unit 103 corrects the driving voltage and performs so-called overdrive driving.

  FIG. 6 is a diagram showing image data output from the response speed correction unit 103 according to the present embodiment.

  The response speed correction unit 103 compares the image data of the previous frame stored in the memory 102 with the current image data, and if there is a change in the image data, overdrive driving is performed according to the result. In the example of FIG. 5, since the frame (3) is different from the previous frame (2) ′, the overdrive drive is executed in this frame (3) by correcting the voltage V1 to the voltage V1 ′. The The difference value between the voltage V1 ′ and the voltage V1 is a correction value corresponding to the voltage V1 before the transition and the voltage V0 after the transition.

  Further, since the frame (4) is different from the previous frame (3) ′, in this frame (4), the voltage V2 is corrected and overdrive driving is executed with the voltage V2 ′. The difference value between the voltage V2 ′ and the voltage V2 is a correction value corresponding to the voltage V2 before transition and the voltage V1 after transition. In the subsequent frame (4) ′ in FIG. 5, the overdrive drive is not performed because the data is the same as that in the frame (4) after the previous two frames.

  As described above, in FIG. 6, overdrive driving is performed in the input signal in the frame (3) that has changed from black to halftone 1 and in the frame (4) that has changed from halftone 1 to halftone 2. Here, the overdrive amount (correction amount) differs between the frame (3) and the frame (4) because the levels before and after the transition are different.

  As a response speed correction method, a method of changing the correction amount according to the input level of the image data of the previous frame and the current display image data by the LUT, or the difference between the image data of the previous frame and the current display image data. There is a method of determining the correction amount according to the above. In the method using the LUT, it is possible to perform the optimum overdrive drive corresponding to the change level, such as increasing the correction amount in the halftone with a slow response speed.

  Next, the polarity inversion unit 106 inverts the polarity of the signal and outputs it for each frame after being converted to twice.

  FIG. 7 is a diagram illustrating a state in which the polarity of the signal after the double speed conversion illustrated in FIG. 6 is reversed in each frame in the polarity reversing unit 106 according to the present embodiment. Each frame in FIG. 7 is the same as each frame shown in FIG. 6, and the drive voltages V1, V2, V1 ′, and V2 ′ are the same as those in FIG.

  In FIG. 7, the polarity inversion is repeated in order for adjacent frames such that the first frame is positive and the next frame is negative with respect to the frame after double speed conversion. That is, the frames (1), (2), (3), (4) and (5) are positive and the frames (1) ′, (2) ′, (3) ′ (4) ′ and (5) 'Is negative polarity. Therefore, when overdrive is performed in the first field after the double speed, the overdrive is biased to the positive polarity side, and there is a problem that a direct current component remains in the liquid crystal. Therefore, the polarity inversion order is switched at a predetermined timing. That is, the polarity of the first field after double speed for one frame of input starts from the negative side.

  An example of switching the order of polarity inversion will be described with reference to FIG. In FIG. 7, the first fields (1), (2), and (3) after double speed are driven with positive polarity, and the second fields (1) ′, (2) ′, and (3) after double speed are negative electrodes. Driven by sex. And, when the AC drive order switching is instructed at the time of switching between the (3) ′ frame and the (4) frame, the first fields (4) and (5) after the double speed are driven with negative polarity. The second fields (4) ′ and (5) ′ after the double speed are driven with positive polarity. Thereby, since the polarity in which overdrive is performed switches, the remainder of a DC component can be improved.

  In the present embodiment, the polarity reversal order is switched at the timing when the remote controller 61 is operated to switch the input signal to the display device 200 and the input signal is switched. The polarity inversion order switching process will be described with reference to FIG. FIG. 9 is a flowchart illustrating an example of the polarity inversion order switching process.

  First, when an input switching instruction operation is performed on the remote controller 61, in step S901, the control panel 62 receives a signal transmitted from the remote controller 61 according to the operation. The control panel 62 notifies the CPU 63 of signal reception from the remote controller. In response to this notification, the CPU 63 first controls the DSP 32 to set the display screen to black display in step S902. By making the display screen black, it is possible to hide switching noise caused by the switch 30 when an input switching instruction is given.

  While the black screen is being displayed, the CPU 63 further controls the polarity inversion control unit 131 in step S903 to output the polarity inversion order change instruction to the polarity inversion unit 106 to change the polarity inversion order. Further, in step S904, the CPU 63 instructs switching of the switch 30 and switches the input to the PC input 50 or the NTSC input 51. Further, in step S905, the CPU 63 cancels the black display setting by the DSP 32.

  In this way, by switching the polarity inversion order during black screen display of input switching, it is possible to improve image quality degradation due to display screen flicker that occurs when the same polarity continues during polarity inversion order switching.

  In FIG. 9, the polarity inversion order is changed according to the operation of the input signal switching instruction of the remote controller 61. However, the trigger for the change is not limited to the operation of the input signal switching instruction. In addition to this, for example, when an operation for a broadcast program switching instruction (channel switching instruction) is performed, the polarity inversion order can be changed according to the operation.

  Next, with reference to FIG. 10, the response speed correction processing in this embodiment will be described. FIG. 10 is a flowchart illustrating an example of a response speed correction process corresponding to the embodiment of the invention. This process is executed by the response speed correction unit 103, the frame rate conversion unit 101, and the polarity inversion unit 106, but may be executed under the control of the CPU 63 based on a program stored in the ROM 64.

  First, in step S1001, the current image data processed by the DSP 32 is input to the frame rate conversion unit 101. In step S1002, the frame rate conversion unit 101 converts the frame rate of the input current image data to double. In the subsequent step S1003, the current image data whose frame rate has been converted is compared with the value of the previous image data one frame before stored in the memory 33.

  If the two values match (“YES” in step S1004), the process proceeds to step S1006. On the other hand, if the two values are different (“NO” in step S1004), the process proceeds to step S1005. In step S1005, the response speed correction unit 103 increases or decreases the driving voltage of the current image data in accordance with the transition direction between the image one frame before and the current image in order to perform overdrive driving. That is, if the transition direction between the image one frame before and the current image is an upward direction, the drive voltage is further increased. Conversely, if the transition direction between the image one frame before and the current image is a downward direction, the drive voltage is increased. Is further lowered. Next, in step S1006, it is determined whether or not to change the polarity inversion order. This determination is made based on whether or not the timing of the polarity inversion order is detected by the timing detection unit 132 and the polarity inversion control unit 131 is instructed to change the polarity inversion order. If it is determined to change the polarity inversion order (“YES” in step S1006), the process proceeds to step S1007. On the other hand, if it is determined that it is not necessary to change the polarity reversal order (“NO” in step S1006), the process proceeds to step S1008.

  In step S1007, the polarity inversion control unit 131 sets the polarity inversion order change, and the process proceeds to step S1008. In step S1008, the polarity inversion unit 106 inverts the polarity of the signal for each frame and outputs the inverted signal to the D / A converter 35. In step S1009, the R, G, and B liquid crystal panels 2R, 2G, and 2B are driven to display based on the output signal from the D / A converter 35. Further, in step S1010, it is determined whether or not to end the image display process. If not (“NO” in step S1010), the process returns to step S1001 to continue the process. When the display process is to be ended (“YES” in step S1010), the process is ended as it is.

  As a result, overdrive is performed equally during forward rotation and reverse rotation.

  As described above, according to the present embodiment, the overdrive drive voltage can be balanced during forward rotation drive and reverse drive, so that the reliability of the display image is improved.

[Second Embodiment]
Next, a second embodiment of the invention will be described. In the present embodiment, a method for switching the order of polarity inversion more frequently than in the first embodiment described above will be described.

  FIG. 11 is a configuration diagram illustrating an example of a signal processing system corresponding to the present embodiment. The configuration of FIG. 11 is characterized in that a scene change detection unit 1101 is newly included in the configuration after the frame rate conversion unit 101 of FIG.

  In this scene change detection unit 1101, the average luminance value of the previous frame (immediately before) output from the memory 102 is compared with the average luminance value of the current frame image output from the frame rate conversion unit 101. Determine whether a scene change has occurred. In this embodiment, it is determined whether or not a scene change has occurred based on the degree of change in the average luminance value, specifically, whether or not the average luminance value has changed by 50%.

  When the scene change detection unit 1101 detects the occurrence of a scene change, the scene change detection unit 1101 notifies the timing detection unit 132 of the occurrence of a scene change. In response to this notification, the timing detection unit 132 notifies the polarity inversion control unit 131 that the timing to invert the polarity has arrived. The polarity inversion control unit 131 sets the order of polarity inversion according to this notification, and the polarity inversion unit 106 changes the order of polarity inversion according to this setting to drive the liquid crystal panel.

  When the order of polarity inversion is changed, there is a risk of image quality degradation due to flicker perception. However, such image quality deterioration can be prevented by performing the change of order in a situation where the screen luminance change is large as in the case of a scene change.

  In the present embodiment, whether or not a scene change has occurred is determined based on the average luminance. However, the present invention is not limited to this, and the maximum luminance value, the minimum luminance value, color information, and scene information embedded in the video in advance are used. You can also.

  As described above, in this embodiment, the frequency of changing the order of polarity inversion can be increased by using the occurrence of a scene change as a trigger, so that the overdrive drive voltage can be balanced during forward rotation and reverse rotation. Reliability is further improved.

[Third Embodiment]
Next, a third embodiment of the invention will be described. In the present embodiment, an example in which the above-described switching of the polarity inversion order is applied to a projection type display device having a diaphragm mechanism for controlling the amount of light to be projected will be described.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. FIG. 12 is a diagram showing an example of the configuration of a projection type image display apparatus corresponding to this embodiment. In FIG. 12, reference numeral 1201 indicates the entire projection type image display apparatus. The projection-type image display device 1201 includes a light modulation element P, an illumination device BL1, and a projection optical system PL1, and is configured to display an image by projecting projection light onto a screen (not shown).

  Here, the light modulation element P is an element that displays a gradation image by controlling the transmission or reflection state of light. The projection optical system PL1 projects transmitted light or reflected light of the light irradiated to the light modulation element P. The illumination device BL1 irradiates light to the light modulation element P, and includes a reflector 1203 and an arc tube 1202. Between the illumination device BL1 and the light modulation element P, a color filter 1204, telecentric lenses 1205a and 1205b, and fly eye integrators 1206a and 1206b are arranged. The light integrated by the fly-eye integrators 1206a and 1206b is condensed on the light modulation element P by the condensing reflection mirror 1207.

  The projection type image display device 1201 further includes a write signal processing unit 1210, a projection light amount control unit 1220, and a control signal generation unit 1230. Here, the write signal processing unit 1210 performs a modulation process of a write signal to the light modulation element P. The projection light amount control unit 1220 controls the amount of light transmitted or reflected from the light modulation element P. The control signal generation unit 1230 controls the write signal processing unit 1210 and the projection light amount control unit 1220.

  Based on the luminance level of the input image signal, the control signal generation unit 1230 controls the control signal so that when the luminance level is high (that is, the luminance level is high), the projection light amount is increased and the modulation of the write signal is decreased. Is generated. When the luminance level is low (that is, the luminance level is low), the control signal is generated so that the amount of projection light is small and the modulation of the write signal is large.

  In the present embodiment, it is preferable that the projection optical system PL1 is a so-called Schlieren optical system. The projection light quantity control unit 1220 includes a movable diaphragm unit 1220a and a diaphragm drive unit 1220b, and is disposed at a position that does not have a conjugate relationship with the light modulation element P. The projection light quantity control unit 1220 controls the aperture amount by opening and closing the movable aperture unit 1220a by the aperture drive unit 1220b according to the luminance level of the input image signal.

  The control signal generation unit 1230 includes a luminance level calculation unit 1230a that calculates the luminance level of the input image signal, and a projection light amount calculation unit 1230b that calculates the projection light amount emitted from the projection optical system according to the calculated luminance level. Has been. Then, the control signal generation unit 1230 generates a control signal for the projection light amount control unit 1220 based on the projection light amount calculated by the projection light amount calculation unit 1230b. Further, a control signal for the write signal processing unit 1210 is generated based on the luminance level calculated by the luminance level calculation unit 1230a and the calculated projection light quantity.

  The luminance level calculation unit 1230a calculates the maximum value of the luminance signal of each pixel in each field or each frame of the input image signal as the maximum luminance. In this case, it can be calculated by sequentially comparing the input image signals in one field or one frame. In addition, it is preferable to calculate a cumulative histogram of the luminance signal of each pixel and calculate a luminance level at which the cumulative histogram becomes a certain level or more as the maximum luminance.

  Here, when the maximum luminance or the average luminance is set to a predetermined level or less by the luminance level calculation unit 1230a, the movable diaphragm unit 1220a is narrowed to reduce the amount of projected light, and the black floating is reduced and tightened. Black display is possible. By switching the order of polarity inversion at this time, it is possible to switch the order of polarity inversion of signals without causing deterioration of display quality due to flicker.

  In addition, even when the control amount of the movable aperture section 1220a is large and the light amount changes greatly, image quality deterioration due to flicker perception due to a change in the polarity reversal order can be prevented, which is preferable as the timing of polarity reversal. In this case, a threshold value is set for the control amount, and when the control amount exceeds the threshold value by comparison with the threshold value, the timing for changing the order of polarity inversion can be determined.

  In the present embodiment, the method of controlling the light amount of the light reflected by the light modulation element P using the movable diaphragm that is the light amount modulation unit has been described. It may be controlled by. Further, as the light amount modulation unit, a unit for controlling the light amount by utilizing, for example, light deflection other than the diaphragm may be used, and the present invention is not limited to this.

  Further, the light modulation element can be applied not only to a reflection type element such as LCOS or DMD but also to a transmission type liquid crystal panel.

  As described above, according to the present embodiment, the frequency of changing the order of polarity reversal can be increased using the light intensity control status as a trigger. Reliability is further improved due to the balance.

[Fourth Embodiment]
Next, a fourth embodiment of the invention will be described. In the present embodiment, a method for switching the order of polarity inversion in a more convenient method than in the above-described embodiment will be described with reference to FIG.

  When the power supply 58 is turned on and the operation power supply is started in the power supply SW (not shown), the CPU 63 detects the power supply ON, and reads the polarity reversal order information at the previous power-off time from the nonvolatile RAM 65. Then, a polarity inversion order different from the polarity inversion information read from the nonvolatile RAM 65 is set in the polarity inversion control unit 131, and the display panel is driven by the polarity inversion unit 106 in a polarity inversion order different from the previous one.

  In the power supply SW (not shown), when the power supply 58 is turned off and the supply of the operation power supply is stopped, the CPU 63 detects the power supply OFF and writes the polarity reversal order information when the power supply is turned off to the nonvolatile RAM 64.

  As described above, in this embodiment, the frequency of changing the order of polarity reversal can be increased by using ON / OFF of the power switch as a trigger, so that the balance of the overdrive drive voltage during forward rotation drive and reverse drive is improved. Therefore, reliability is further improved.

  In the present embodiment, the example in which the polarity inversion order is changed when the power is turned on has been described.

[Fifth Embodiment]
Next, a fifth embodiment of the invention will be described. In the present embodiment, a method for switching the order of polarity inversion in a more convenient method than in the above-described embodiment will be described with reference to FIG.

  Using the timer function of the CPU 63, the polarity inversion control unit 131 changes the order of polarity inversion every elapse of a predetermined time. The switching time is preferably about 10 to 60 minutes from the characteristics of the liquid crystal.

  Further, various conditions may be detected when the arrival of a predetermined time is detected by combining this timer function and the above-described embodiment. That is, the order of polarity inversion can be changed when input switching or channel switching is performed after a predetermined time, or when a scene change occurs. Thereby, the order of polarity inversion can be changed periodically, and image quality deterioration at the time of change can be prevented.

  As described above, according to the display devices according to the first to fifth embodiments described above, in the liquid crystal display device that performs AC voltage driving, the order of normal rotation driving and inversion driving is changed at a predetermined timing. Thereby, it is possible to improve signal deterioration due to a direct current component due to overdrive driving. In particular, according to the configuration of the present embodiment, it can be applied to a general display device without adopting a special structure. Furthermore, it is possible to provide a display device with high image quality without reducing reliability.

[Other Embodiments]
Note that the present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, and a printer), and a device (for example, a copying machine and a facsimile device) including a single device. You may apply to.

  The object of the present invention can also be achieved by supplying a storage medium storing software program codes for realizing the above-described functions to the system, and the system reading and executing the program codes. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. In addition, an operating system (OS) running on a computer performs part or all of actual processing based on an instruction of the program code, and the above-described functions are realized by the processing.

  Furthermore, you may implement | achieve with the following forms. That is, the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. Then, based on the instruction of the program code, the case where the above-described functions are realized by the CPU included in the function expansion card or the function expansion unit performing part or all of the actual processing is also included.

  When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the flowcharts described above.

It is a side view which shows an example of the rear projection type display apparatus 200 which concerns on embodiment of invention. It is a figure which shows an example of the structure of the projection type display engine D1 which concerns on embodiment of invention. It is a block diagram which shows the structure of the display engine of the display apparatus which concerns on embodiment of invention. It is a figure which shows an example of the signal which drives the specific pixel of the liquid crystal panel input into the frame rate conversion part 101 which concerns on embodiment of invention. It is a figure which shows an example of the image data output from the frame rate conversion part 101 based on embodiment of invention. It is a figure which shows an example of the image data output from the response speed correction | amendment part 103 based on embodiment of invention. It is a figure which shows an example of the image data output from the polarity inversion part 106 based on embodiment of invention. It is a figure explaining the case where the polarity reversal order of the signal based on embodiment of invention is changed. It is a flowchart which shows an example of the switching process of the polarity reversal order which concerns on embodiment of invention. It is a flowchart which shows an example of the correction process of the response speed which concerns on embodiment of invention. It is a figure which shows an example of a structure of the signal processing system which concerns on the 2nd Embodiment of invention. It is a figure which shows an example of a structure of the projection type image display apparatus corresponding to the 3rd Embodiment of invention. It is a figure for demonstrating the conventional correction method.

Claims (9)

Liquid crystal display means driven by alternating voltage;
Conversion means for converting the input image data into N frame rates by dividing the input image data into N frames for each frame;
Correction means for correcting the drive voltage for driving the liquid crystal display means based on the difference between the image data temporally changing with respect to the image data converted by the conversion means,
Reversing means for reversing the polarity of the image data including the image data corrected by the correcting means so that the driving polarity of the image data before and after is different;
Drive means for driving the liquid crystal display means using the image data with the polarity reversed;
Control means for switching the order of reversing the polarity;
At least two or more input means for inputting the image data;
An input switching means for switching the two or more input means to input the image data from any one of them;
Receiving means for receiving a switching instruction for the input switching means;
With
When the switching instruction is received by the receiving means, the control means switches the order of inverting the polarity. When image data of a program broadcast using a plurality of channels is input by any one of the two or more input means,
The accepting means further accepts an instruction to switch the channel;
2. The liquid crystal display device according to claim 1, wherein when the channel switching instruction is received by the receiving unit, the control unit switches the order of inverting the polarity. When switching of the order of inverting the polarity is performed by the control means,
The liquid crystal display device according to claim 1, wherein the liquid crystal display unit is driven by the driving unit so as to display black. Liquid crystal display means driven by alternating voltage;
Conversion means for converting the input image data into N frame rates by dividing the input image data into N frames for each frame;
Correction means for correcting the drive voltage for driving the liquid crystal display means based on the difference between the image data temporally changing with respect to the image data converted by the conversion means,
Reversing means for reversing the polarity of the image data including the image data corrected by the correcting means so that the driving polarity of the image data before and after is different;
Drive means for driving the liquid crystal display means using the image data with the polarity reversed;
Control means for switching the order of reversing the polarity;
A light amount control means for controlling at least one of a light amount projected to the outside of the liquid crystal display device via the liquid crystal display means and a light amount projected to the liquid crystal display means,
The control in at least one of the case where the light amount controlled by the light amount control unit is less than a predetermined light amount and the case where the control amount of the light amount by the light amount control unit exceeds a predetermined control amount. A liquid crystal display device characterized in that the order of inverting the polarity is switched by means. A conversion step in which the conversion means converts the input image data into N frame rates by dividing the input image data into N frames for each frame;
A correcting step of correcting a driving voltage for driving the liquid crystal display unit based on a difference between temporally changing image data for the converted image data;
An inversion step in which the inversion means inverts the polarity so that the drive polarity of the image data before and after is different for the image data including the image data corrected in the correction step,
A driving step of driving the liquid crystal display means using the image data with the polarity reversed;
A control step of switching the order in which the control means reverses the polarity;
An input step in which at least two or more input means input the image data;
An input switching step for causing the input switching means to switch the two or more input means and to input the image data from any one of them;
A receiving step for receiving a switching instruction to the input switching unit;
With
A control method for a liquid crystal display device, wherein when the switching instruction is received by the receiving means, the control means switches the order of inverting the polarity. A conversion step in which the conversion means converts the input image data into N frame rates by dividing the input image data into N frames for each frame;
A correcting step of correcting a driving voltage for driving the liquid crystal display unit based on a difference between temporally changing image data for the converted image data;
An inversion step in which the inversion means inverts the polarity so that the drive polarity of the image data before and after is different for the image data including the image data corrected in the correction step,
A driving step of driving the liquid crystal display means using the image data with the polarity reversed;
A control step of switching the order in which the control means reverses the polarity;
A light amount control unit comprising a light amount control step for controlling at least one of a light amount projected outside the liquid crystal display device via the liquid crystal display unit and a light amount projected onto the liquid crystal display unit;
The control in at least one of the case where the light amount controlled in the light amount control step is lower than a predetermined light amount and the case where the control amount of the light amount in the light amount control step is higher than a predetermined control amount. A method of controlling a liquid crystal display device, wherein the order of reversing the polarity in the process is switched. Liquid crystal display means driven by alternating voltage;
At least two or more input means for inputting image data;
An input switching means for switching the two or more input means to input the image data from any one of them;
Receiving means for receiving a switching instruction to the input switching means;
In a liquid crystal display device comprising
A conversion step of converting the input image data into N times the frame rate by dividing it into N frames per frame;
A correction step for correcting a driving voltage for driving the liquid crystal display means based on a difference between image data temporally changing with respect to the image data converted in the conversion step,
An inversion step of inverting the polarity of the image data including the image data corrected in the correction step so that the driving polarity of the image data before and after is different.
A driving step of driving the liquid crystal display means using the image data with the polarity reversed;
A step of switching the order of inverting the polarity when the switching instruction is received by the receiving means;
A computer program for running. In a liquid crystal display device comprising liquid crystal display means driven by an alternating voltage,
A conversion step of converting the input image data into N times the frame rate by dividing it into N frames per frame;
A correction step for correcting a driving voltage for driving the liquid crystal display means based on a difference between image data temporally changing with respect to the image data converted in the conversion step,
An inversion step of inverting the polarity of the image data including the image data corrected in the correction step so that the driving polarity of the image data before and after is different.
A driving step of driving the liquid crystal display means using the image data with the polarity reversed;
A light amount control step of controlling at least one of a light amount projected outside the liquid crystal display device via the liquid crystal display means and a light amount projected onto the liquid crystal display means;
The polarity in at least one of the case where the light amount controlled in the light amount control step is lower than a predetermined light amount and the case where the control amount of the light amount in the light amount control step is higher than a predetermined control amount. Control process for switching the order of reversing
A computer program for running. A computer-readable storage medium storing the computer program according to claim 7 or 8 .

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